Relaxation circuit oscillator



March 13, 1934. w -n5 1,950,399

RELAXATION CIRCUIT OSQILLATOR v Filed Feb. 11, 1930 l l INVENTOR.

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A TORNE) Patented Mar. 13, 1534- ore rice

2 Claims.

(Granted under the act of March 3, 1883, as amended April 39, 1928; 37%(l. G. 757) My invention relates broadly to relaxation circultoscillators and more particularly to a circuit arrangement fortransferring energy delivered by a relaxation circuit oscillator to awork circuit.

One of the objects of my invention is to provide a circuit arrangementfor a relaxation oscil lator having means for transferring relativelyhigh output voltage to a work circuit with a high IQ degree ofstability.

Another object of my invention is to provide a circuit arrangement for arelaxation oscillator in which harmonic frequencies may be intensified:and a higher voltage output obtained from a in position in the circuitadjacent the anode of the oscillator.

Still another object of my invention is to provide an arrangement ofrelaxation circuit for the regeneration of audio frequency oscillationswhich the anode lead includes an impedance element across which theaudio frequency energy is delivered for transmission to a work circuitfrom the anode circuit of the relaxation oscillator.

Other and further objects of my invention reside in the circuitarrangement for a relaxation circuit oscillator as described more fullyin the specification hereinafter following by reference to theaccompanying drawing, in which:

Figure 1 diagrammatically illustrates one form of circuit for therelaxation circuit oscillator 02 my invention; Fig. 2 shows a modifiedcircuit arrangement for the relaxation oscillator of my 111- vention;Fig. 3 shows a still further modification of the relaxation oscillatorof my invention; Fig. 4 is a further modified showing of the relaxationoscillator of my invention; Fig. 5 illustrates the circuit arrangementof my invention as applied to a three-grid type of electron tube in arelaxation oscillator system; and Fig. 6 shows a modification of thecircuit of Fig. 4.

The thermionic vacuum tube, when connected in a circuit with the propercombination of electrical impedances and electrcrnotive forces, willgive rise to alternating current energy. There are many known circuitsin which such a tube will produce electrical oscillations, the mostcommon of which is the inductance capacity oscillator with a sinusoidaloutput. Not so well known, but destined to become of importance in 50several new fields is another type of oscillator,

the oscillations of which consist of aperiodic pulses of E. M. F.occurring in cyclic order, and whose output, therefore, is far removedfrom sine wave form. Such an oscillation occurs when the electric ormagnetic held or" a capacity or an inductance is built up until a set orlimiting conditions is reached, the field then being dissipated until asecond set of limiting conditions causes a second reversal and the fieldis built up again. The action of the field in building up to a potentialapplied through an impedance or dissipating itself through an impedancemay be referred to as relaxation, and since the period of theoscillation in question is determined by the time of relaxations, thecircuit producing such action is called a relaxation oscillator. In oneform of relaxation oscillator an electron tube with two grids is usedwith resistance and capacity only; such as oscillator is described inthe Van der Pol Patent No. 1,744,935, issued January 28, 1930. Thefrequency of the relaxation oscillator dep nds on the values of thecircuit elements employed. While the output of the relaxation oscillatormay be of considerable amplitude, it is possible to control the outputfrequency by a higher frequency of very small amplitude. Thischaracteristic oi the relaxation oscillator makes it available for anumber of important applicatime.

I have discovered that the operation of a relaxation oscillator may bestabilized by introducing resistance into the anode lead across whichthe high frequency energy may be taken off at relatively higher voltagethan has been obtainable heretofore in relaxation oscillators where thevoltage is taken all at other points in the relaxation oscillator. Ihave found that the output voltage may be further increased byconnecting an inductance in circuit with the anode of the relaxationcircuit oscillator and the inductance coupled or connected to an outputcircuit. A transformer may be connected in the anode lead of therelaxation circuit oscillator to obtain the required voltage in theoutput system. For purposes of stabilizing the relaxation circuit,resistance elements may be interposed in series or parallel relationwith respect to the inductance in the anode lead of the relaxationcircuit oscillator. My invention is applicable to multiple grid electrontubes and the circuit arrangement which I have illustrated isparticularly adapted for frequency division operation.

Referring to the drawing in more detail, reference character 1designates an electron tube which includes cathode 2, anode 5, and gridelectrodes 3 and e. Grid electrode 3 functions as the inner or controlgrid, while grid electrode 4 operates as a shield grid. High potentialsource 6 winch has been illustrated for the purpose of explaining theprinciples of my invention as 9.

battery, has its positive terminal connected to anode 5 throughresistance 7, resistance 7 having terminals 711 and 7b forming theoutput terminals of the circuit. Control or inner grid 3 is connectedthrough resistance 9 with the point of positive potential 8 in thebattery system 6. The cathode is heated from any suitable source such asrepresented by battery source 12. Condenser 11 is connected in shuntbetween inner grid 3 and shield grid 4. Resistance 10 connects betweenshield grid 4 and negative terminal of battery system 6.

In Fig. 2, I have shown an inductance element 14 connected in place ofthe resistance element 7 illustrated in Figure 1 Where the inductanceelement 14 has terminal leads 14a and 14b at opposite ends thereofleading to the output system. The inductance 14 yields a relatively highvoltage and intensifies the harmonics.

In Fig. 3, I have shown the circuit arrangement of Fig. 2 includinginductance element 14 which connects to the output system through leads14a and 1411 where the inductance 14 connects in series with resistanceelement 15. This combined arrangement of inductance and resistance inthe output lead increases the stability of operation of the relaxationoscillator over that stability which is obtainable with the circuit ofFigure 2.

Fig. 4 illustrates a relaxation oscillator system in which the anodecircuit lead includes the primary winding 17 of transformer 16 wheretransformer 16 has secondary winding 18 connecting to the output system.This arrangement yields a relatively high output voltage and isstabilized in operation by means of series connected resistance 19 andby parallel connected resistance 20 in circuit with primary winding 17.Good results are also obtained with the circuit of Fig. 4 using seriesresistance 19 alone and omitting shunt resistance 20.

In Fig. 5 I have shown the circuit of my invention employed in athree-grid relaxation oscillator system wherein an electron tube 21 isprovided having cathode 22 and anode 25 with grid electrodes 23, 24, and26 disposed therebetween. The high potential source is illustrated at 30and there are connections to each of the grid electrodes and to theanode through resistance elements from the source of high potential 30.That is to say, grid 26 connects through resistance 29 with the negativeterminal of battery 30. Grid 24 connects through resistance 28 with thenegative terminal of battery 30. Grid electrode 23 connects throughresistance 31 to a point of positive potential in battery 30*. Anode 25connects through resistance 32 with the positive terminal of battery 30.Leads 32a and 32b ex"- tend from opposite ends of resistance 32 and formthe output terminals for the relaxation oscillator. Condenser 27connects between grid electrodes 23 and 24 of the relaxation oscillator.

Fig. 6 shows a modification of the circuit of Fig. 4 wherein resistance20 is in shunt with the primary winding 17 and no resistance is employedin series with the primary winding and the anode.

While I have described my invention in certain of its preferredembodiments, it will be understood that modifications may be made andthat no limitations upon my invention are intended other than areimposed by the scope of the appended claims.

The invention herein described may be manufactured and used by or forthe Government of the United States of America. for governmentalpurposes without the payment of any royalties thereon.

What I claim as new and desire to secure by Letters Patent of the UnitedStates is as follows:

1. In a relaxation circuit oscillator, an electron tube having cathode,anode, and a multiplicity of grid electrodes, a capacity elementconnected between two of said grid electrodes, impedance elementsconnected in circuit between said cathode and each of said gridelectrodes, a transformer comprising primary and secondary windings,said primary winding being connected in circuit with said anode, aresistance element disposed between said primary winding and said anode,a resistance connected in shunt with said primary winding, and terminalconnections extending from said secondary winding for utilizingoscillations generated by said relaxation circuit oscillator.

2. In a relaxation circuit oscillator, an elec-.- tron tube including acathode, an anode, and a multiplicity of grid electrodes, a capacityelement connected between two of said grid electrodes, impedanceelements connected in circuit with each of said grid electrodes, saidimpedance elements having substantially negligible inductive effects, anoutput circuit, a source of potential, a transformer comprising primaryand secondary windings, a resistance, said primary winding, said sourceof potential, and said resistance being connected in series in saidoutput circuit, a second resistance connected in parallel with saidprimary winding, and terminal connections extending from said secondarywinding for utilizing oscillations generated by said relaxation circuitoscillator.

WESTLEY F. CURTIS.

